The rise of Rick Santorum in the race for the Republican presidential nomination hasn't exactly gone unnoticed by rival Mitt Romney or his friends. Turn on a TV in Michigan this weekend, and chances are you won't have to wait long to see an ad attacking the former Pennsylvania senator.

"America is drowning in national debt," a narrator intones in one ad, a product of Romney's campaign. "Yet Rick Santorum supported billions in earmarks."

Meanwhile, the superPAC that backs Romney, called Restore Our Future, is behind an ad that focuses on who has "the right experience."

"Romney rescued the Olympics," the ad says. "Santorum was in Washington, voting to raise the debt limit five times."

But unlike the other GOP candidates who at one time or another emerged to take on Romney, Santorum and the superPAC supporting him seem to have the resources to fight back. The battle is taking place on the airwaves in Michigan, which along with Arizona holds its presidential primary Feb. 28.

Economic Attacks

It's no coincidence that both the Romney and the Restore our Future ads go after Santorum for his fiscal views. Unlike former House Speaker Newt Gingrich, Santorum has no real personal baggage.

But after 16 years in Congress, he does have a lengthy voting record. Paul Freedman, a political science professor at the University of Virginia, says it gives Romney plenty of ammunition, especially on economic issues, which he's been using in his ads.

"We see images of budget deficits, deficit clocks. We see counters counting off the number of bills that, according to the Club for Growth, Rick Santorum supported that included increases in spending," Freedman says. "So we see this concerted effort by Romney, through his ads, to make the case that Santorum's not the real conservative when it comes to fiscal issues."

The superPAC that supports Santorum — the Red, White and Blue Fund — has reportedly bought $650,000 worth of air time in Michigan, to augment the $400,000 the Santorum campaign has spent in the state. While that's far less than Romney and his superPAC are spending, it allows Santorum's backers to run ads touting his values — such as one that calls him a "proven conservative."

"Rick Santorum: Father. Husband. A champion for life. The leader with a bold plan to restore America's greatness," it says.

Another ad on the air in Michigan features lots of pictures of Santorum with his family. While that's almost a campaign cliche, Freedman says it serves Santorum well.

"He's telling people that he is a family man. He's telling people that he has family values and he's making connections to the people of Michigan — the Michigan Republican primary voters — on the basis of these values and on the basis of his connection to his family," Freedman says.

Of course, Romney is also a family man trying to connect with Michigan's primary voters. We'll find out Feb. 28 who does the better job.